The present invention relates generally to auxiliary steering systems for adjusting the steering angles of the front or rear wheels of a motor vehicle, and more particularly to such an auxiliary steering system operable in connection with an anti-skid control system which independently performs the braking control for at least either the front-side right and left wheels or rear-side right and left wheels of the motor vehicle.
Anti-skid control systems are generally known as systems for controlling the braking hydraulic pressures to braking devices for the wheels of a motor vehicle so as to prevent the wheels from being locked and slipped in response to braking operation by the vehicle driver. An important problem in anti-skid control systems of the type that the braking control is effected independently for the right and left wheels relates to the fact that the braking hydraulic pressures for the right and left wheels are different from each other due to the difference between the friction coefficients .mu. of the road surfaces coming into contact with the right and left wheels. This causes generation of a yawing moment with respect to the motor vehicle, thereby resulting in the motor vehicle being apt to be deflected toward the high .mu. road. One known approach for elimination of this problem, such as is disclosed in Japanese Patent Provisional Publication No. 58-164460, is that in order to prevent the generation of the yawing moment the braking pressure for the wheel on the high .mu. road surface is controlled in accordance with the braking pressure for the wheel on the low .mu. road surface. However, this approach causes deterioration of the anti-skid control function and hence lengthens the braking distance of the motor vehicle. Another attempt, as disclosed in the Japanese patent Provisional Publication No. 60-161256, is to perform the auxiliary steering control of the wheels on the basis of detection of the lateral acceleration or yaw rate of the motor vehicle. Similarly, there is a problem which arises with such an attempt, however, in that specific sensors are required to detect the lateral acceleration or yaw rate and further it is not effective to perform the auxiliary steering control after the detection thereof because of resulting in delay of the execution of the steering control in practice.